On September 26, 1995, Constitution was undocked, three years
and one day after initially being brought into drydock for inspection and
minor repair. Not only was Constitution repaired for her bicentennial
but there was a significant change in the scope of work between the original
plan and the final executed package. Restoration became the central focus
where major structural hull components were restored. Known as the Strengthening
Initiative, this repair is the most significant structural restoration
in Constitution's history.

As history can attest, Constitution represents a successful design.
Joshua Humphreys, the designer of the Navy's first six frigates, that included
Constitution, had two criteria to satisfy, to out gun the next rate
ship and to out-sail adversaries. The solution required a never-before-built
design.

The successful integration of the two design criteria demanded an innovated
technical solution to the problems of strength of materials and hull design.
Humphreys understood that optimization of the two criteria became mutually
exclusive when building a hull. The fine entry and run required for sailing
qualities and the weight of a heavy armament causes particular problems
for wooden hull sailing ships. Combining the weight of the guns and the
buoyancy curve of a fast sailing hull results in a force that distorts
the hull. The distortion known as "hog" is the bending along the length
of the keel. It is the same curve that resembles the curve of a hog's back.
With minimal buoyancy, the ends of the ship tend to drop down under the
weight loads of the guns, while the center midbody, being more buoyant,
rises upward. Humphreys recognized the need to stiffen the hull to resist
the forces causing hogging.

From historical research, five components were identified to have been
part of Constitution's original construction.

Thick Strakes, Restored using laminated white oak planking on gun deck
and lower deck. There are two paired runs, (fore and aft), (port and starboard),
of deck planking: One pair running along side of the hatches, the other
pair running midway between the waterways and hatch strakes. The thick
strakes are thicker by two inches, (five and one-half inches total) than
the standard deck planking and are bolted and joggled into each other,
and joggled over and into the deck beams below by two inches. These deck
strakes add longitudinal strength to the hull.

Standard Knees, Restored at the ends of the ship, both at the bow and stern,
are long laminated white oak knees fayed at the end of each pair of thick
strakes on lower deck. These joggle over two deck beams and are well bolted
to the bow and stem with one and one eighth inch bolts. These knees unite
the deck thick strakes to the hull.

Two additional laminated white oak standard knees restored on the
centerline, one reaching from the stem to the foremast and the other from
the transom to the mizzen mast, joggled over and into each deck beam and
well bolted. These additional two knees also strengthen the hull at ends
of the ship.

Midship Knees, Restored on lower deck, are laminated white oak knees made
as a single composite of the original hanging and standard knee pairs.
The knees fay over each beam the diagonal riders come under with the others
placed amidships for a total of twelve on each side. The knees are sided
thirteen inches, the body reaches the upper edge of gun deck clamp, the
arm is six feet long. The knees are bolted with eight bolts each one and
one fourth inch diameter. These twelve knees carry the weight of the overhead
gun deck cannon distributing the loads to lower deck.

Stanchions, Made of turned white oak copied from the centerline stanchions.
On lower deck, two additional tiers were restored, each under an overhead
gun deck beam at the midship thick strakes. These stanchions work in conjunction
with the midship knees to form a structural unit supporting the overhead
cannon.

Diagonal Riders. Made of laminated white oak, 12 x 24 inches in cross section
and approximately 34 feet long. Restored in the hold, a total of twelve
diagonals, six per side, three sweeping forward, three sweeping aft, with
the two midbody ones butted against each other at the keelson. The diagonals
are spaced a distance of two beams apart and follow the curve of the hull
along the ceiling plank. They are chocked at the keelson and are cut with
a bird's mouth into the overhead lower deck beams. Being bolted every two
feet through the bottom plank with one and one-eighth inch copper bolts,
the diagonal rider becomes the unifying member joining hull sections together,
stiffening the hull and resisting the forces which cause hogging.

Throughout the last 200 years as Constitution's purpose and function
changed from fighting warship, to training vessel, to receiving ship, to
dock side exhibit, so did Constitution's configuration. Also, Constitution's
repair(s) did not always retain her original construction. The five structural
components were expensive in materials, techniques, and labor to install.
As early as 1820, the diagonal riders were not renewed in Constitution's
repairs. Those five components were not part of Constitution's structure
when drydocked in 1992.

Over the years, age began to show on the hull of Constitution.
By 1992 Constitution had developed over 13 inches of hog. Many suggestions
had been proposed for stiffening the hull: air bags, steel girders, and
space frames. None of these were historically accurate and none were congruent
with the fabric of the ship.

In 1993, aware of the structural needs of an aging hull and that Humphreys
had already answered these questions, NHC Detachment Boston modeled the
five historical structural components. Using a 1:16 scale model of Constitution,
a 10% increase in hull stiffness to resist hogging was shown. Just as Humphreys
specified in 1794, the Detachment recognized in 1994 the effectiveness
of the structural components and successfully extended the dry dock repair
activity to include the restoration of those five structural components.

The drydock repair consisted of both rehabilitation, (the repair of
deteriorated structure) and restoration, (putting back into Constitution
components of her 1812 configuration). To restore the structural components
during the 1992 drydock repair was a justified expenditure of labor, techniques,
and materials. Due to the limited availability of the required natural
timber, glue lamination technology supplied much of the wood shaped to
Humphreys' dimensional specifications.

In 1797, while observing the launch of USS United States, Joshua Humphreys
wrote to the Secretary of War, that "...without straining or hogging more
than one & a quarter inch, as you will see by the enclosed certificate,
to my great and unspeakable satisfaction. The firmness of the ship was
convincing proof of the utility of the diagonal riders in long ships, "1
Today the same may be said for Constitution. When undocked in September
1995, the hog was measured to be less than two inches. The effectiveness
of the structural components is again shown with "convincing proof" and
"unspeakable satisfaction".

Given the satisfactory condition of the hull and the successful completion
of the repairs, Constitution is being readied to sail in celebration
of her bicentennial. On July 21, 1997, for the first time since 1881, Constitution
will make passage under her own sail, sailing in Massachusetts Bay under
topsails, jibs, and spanker -- her battle configuration. With a Navy crew
and under specified weather conditions of winds less than 15 knots and
seas less than two feet, Constitution will sail again as a salute
to the Nation.

Joshua Humphreys is owed credit for the 200 year story of success of
Constitution. It is his innovative design in building a structurally
stiff hull that resolved the design criteria of fast speed under sail while
carrying heavy armament. The history of this Nation rests on Constitution
as a unique example of American technology. Constitution has become
a lasting National symbol as a product of Humphreys' design.